Forming tool

ABSTRACT

A flex ring forming tool, forming apparatus, and method of coldforming a profiled workpiece through radial material flow is disclosed wherein the flex ring has an internal profile complementary to the profile of the finished workpiece and wherein the lands of the flex ring forming profiles have uniform, relatively narrow widths from the minimum depth leading ends to the maximum depth trailing ends of the profiles while the widths of the forming profiles at a given radial distance from the center of the flex ring gradually increases from their leading to their trailing ends. The flex ring is deflected inwardly to penetrate the workpiece blank as the workpiece is fed therethrough with the feed of the workpiece and the flexing of the ring by the apparatus being coordinated so that the workpiece is progressively formed into the desired profile by the straining of localized circumferential areas of the workpiece and the resulting radial material flow in the workpiece blank.

United States Patent {72] Inventor ErichTlaker Springfield, Vt. [211Appl.No. 831,133 [22] Filed June 6, 1969 [45] Patented Dec.2l,197l [73]Assignee The Fellows Gear Shaper Company Springfield, Vt.

[54] FORMING TOOL 7 Claims, 5 Drawing Figs.

[52] U.S.Cl 72/76,

' 72/467 [51] lnt.Cl.....; B21] 13/02 {50] Field olSearch 72/77, 102,103,467,468, 1 18,76, 121, 88, 89,90; 29/1592 [56] References CitedUNITED STA-TBS PATENTS 985.905 3/1911 Johnston 29/l59.2 2.375.481 5/1945Lee eta1.... 72/88 2,906,143 9/1959 Musser 29/1592 3.025.946 3/1962Raydtet al.... 72/467 3.396.563 8/1968 Tlaker 72/118 FOREIGN PATENTS321,017 10/1929 Great Britain Primary Examiner-Richard .I. HerbstAtt0rney-Cushman, Darby & Cushman method of cold-forming a profiledworkpiece through radial material flow is disclosed wherein the flexring has an internal profile complementary to the profile of thefinished workpiece and wherein the lands of the flex ring formingprofiles have uniform, relatively narrow widths from the minimum depthleading ends to the maximum depth trailing ends of the profiles whilethe widths of the forming profiles at a given radial distance from thecenter of theflex ring gradually increases from their leading to theirtrailing ends. The flex ring is deflected inwardly to penetrate theworkpiece blank as the workpiece is fed therethrough with the feed ofthe workpiece and the flexing of the ring by the apparatus beingcoordinated so that the workpiece is progressively formed into thedesired profile by the straining of localized circumferential areas ofthe workpiece and the resulting radial material flow in the workpieceblank.

FORMING TQOlL BRIEF DESCRIPTION OF THE INVENTION The present inventionrelates to flex ring forming tools for forming externally profiledworkpieces and, in particular, to flex ring forming tools wherein theforming profiles of the flex ring are shaped to inhibit any longitudinalflow of the workpiece material and obtain formation of the workpiece byprimarily radial flow of the workpiece material.

' Flex ring forming tools heretofore utilized in the cold-forming fieldhave employed forming profiles wherein the lands of the forming profilesare greatest in width at the entrance of the flex ring with the landsdecreasing in width from the entrance of the flex ring to the exit ofthe'flex ring as the profiles progress from minimum depth to full depth.In addition to the above, the widths of the forming profiles for a givenradial distance from the axial centerlines of these tools remainconstant or substantially constant throughout the length of theprofiles.

.One method of forming such flex rings is to first machine an internallyprofiled part and subsequently machine a conelike entrance section intoit. As a workpiece is fed into one of the prior art flex rings,substantially all of the forming action is produced by the lands or tipsof forming profiles. The reason for this is the constant ofsubstantially constant transverse cross-sectional width of the formingprofiles, at a given radial distance from the center of the workpiece,from the entrance to the exit of the flex ring and the relatively widecontact areas of the forming profile lands which have their maximumwidth at the point of first contact with the workpiece. The above, inconjunction with the relatively narrow spaces between adjacent profilelands, causes substantial straining of the entire core of the workpiecewhen the workpiece is being formed and inhibits radial outward flow ofthe workpiece material thereby resulting in a progressive reduction ofthe entire cross section of the workpiece along with a correspondingelongation of the workpiece. As a result of this extruding action, theformed part is usually smaller in its exterior dimensions than theblanks from which it is formed. Furthermore, it has been found that itis usually not possible to produce well-defined teeth or toothlikeprofiles, using this type of flex ring, even when starting with blanksof a larger diametrical dimension than the intended dimension of thefinished product.

The flex ring of the present invention solves the above-mentionedproblems by restricting the straining of the workpiece blank tolocalized areas at the periphery of the workpiece blank therebyproducing material flow only in such localized areas, while the core ofthe workpiece blank remains undeformed. By avoiding the straining of theentire cross section of the workpiece blank to such an extent thatmaterial flow would occur throughout the entire cross section of theworkpiece blank, the lengthwise extrusion of the workpiece blankexperienced heretofore is prevented. The resulting finished workpiecehas external dimensions substantially the same as the originaldimensions of the workpiece blank and the teeth or profiles of the blankare accurately formed.

A preferred form of carrying out the principles of the present inventionutilizes a flex ring forming tool that has an internally profiled shapewhich is the counterpart or the complement of the shape of the finishedworkpiece. The flex ring has forming profiles with relatively narrowtips or lands of uniform width from the entrance of the flex ring wherethe forming profiles are of minimum depth to the full depth of theforming profiles at the exit portion of the flex ring. The widths of theforming profiles gradually increase, for a given radial distance fromthe axial centerline of the flex ring, from the leading ends of theforming profiles until the profiles reach full depth. With thisconstruction, forming action takes place not only on the forming profilelands but also on the profile flanks or sides. The relatively narrowwidths of the forming profile lands together with relatively largespaces between the adjacent profile lands and flanks, which define theareas of contact between the flex ring and workpiece blank, promotelocalized material flow radially outward into the space between theforming profiles and inhibit longitudinal flow of the workpiecematerial.

Since the width of the forming profile lands remain uniform and thewidths of the profiles at a given radial distance from the flex ringaxial centerline, increase gradually, a progressive displacement of theworkpiece material takes place in localized peripheral areas adjacentthe forming profile lands and flanks as the workpiece blank ispenetrated. This forming action leads to a gradual squeezing or pinchingof the workpiece blank material in the spaces intermediate the formingprofiles and aids in the displacement of the material radially outwardinto the spaces of the flex ring between the forming profiles. Since thecore of the material remains unstrained, the material deformed by theforming profiles of the flex ring moves radially outward and the crosssection of the formed part measures essentially the same as the originalcross section of the work piece blank. Primarily, only the shape of thefinished work piece differs from that of the workpiece blank.

The flex ring forming tool of the present invention can be used to forma workpiece by the method and in the apparatus disclosed in my US. Pat.No. 3,396,563, issued Aug. 13, I968 and titled Method Of FormingProfiled Objects" and the entire disclosure of this patent is herebyincorporated into the present application by reference. Accordingly, theworkpiece is cold-formed in a continuous process as it is fed throughthe flex ring by the application of forces through the flex ring to theworkpiece in limited circumferential zones of the workpiece while movingthe zones relatively circumferentially of the workpiece.

The above objects and advantages of the present invention will becomemore apparent and other objects and advantages of the present inventionwill become apparent from the following detailed description when takenin conjunction with the accompanying drawings in which:

FIG. 1 is a longitudinal section of the flex forming tool showing aworkpiece about to enter the working portion of the flex ring;

FIG. 1A is a partial section at A-A of FIG. 1 showing only a portion ofthe flex ring;

FIG. '18 is a partial section at B-B of FIG. 1 showing only a portion ofthe Hex ring; 7

FIG. 1C is a partial section at CC of FIG. 1 showing only a portion ofthe flex ring;

FIG. 1D is an enlarged partial section at D--D of FIG. Idiagrammatically illustrating the fiex ring with a formed workpiecetherein and also illustratingin broken lines the shape of the flex ringprofile comparatively at A-A, B-B, and C-C of FIG. ll;

FIG. 2 is a partial section of a machine which can be used with the flexring forming tool of the present invention; and

FIG. 3 is an enlarged and exaggerated partial view showing the formingtool as it is flexed to form the desired profile in the workpiece whenin a forming machine such as that illustrated in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION As shown in FIG. 1 and 1A throughID, the flex ring forming'tool has a plurality of profiles 22'which arecomplemental to the shape given to the workpiece W. For the purposes ofillustration, the formation of a gearlike workpiece with axiallyextending teeth T is depicted. However, if other types of externallyprofiled workpieces are desired, such as workpiece with helical gearteeth or helically disposed elements, it is merely necessary to have thecorresponding forming profiles on the flex ring similarly helicallydisposed and the desired shape will be obtained on the workpiece sincethe flex ring produces a finished workpiece which is its complement orcounterpart.

The flex ring forming tool 20 is made of a suitable metal that iscapable of being elastically deformed, such as by the application offorces thereto in limited zones spaced circumferentially about the flexring. The forming profiles 22 of the flex ring extend radially inwardfrom the inner surface of the flex ring with the depth of the profilesprogressively increasing from the leading end or entrance 24 of the flexring where the raw workpiece enters to a point (section c-c)intermediate the entrance and the trailing end or exit 26 of the flexring from which the finished workpiece exits.

From their minimum to their maximum depth and throughout the entirelength of the forming profiles 22, the forming profile tips or lands 28have uniform or constant widths, X, which are relatively narrow whencompared to either the spacing between adjacent profiles of the widthsof the full depth portions of the profiles at their base. As best shownin FIG. 1D for any given radial distance from the axial centerline ofthe flex ring, the widths of the forming profiles gradually increasefrom their leading ends to the point C-C where they reach full depth.For example, the width of the profile at the radial distance R changesfrom X at A-A to Y at D-D.

The substantially constant .widths of lands 28, as compared with thegradually increasing widths of the forming profiles for a given radiuscan also be seen by comparing FIGS. 1A to IC.

At AA in FIG. IA, the profiles 22 of the flex ring 20 are ofcomparatively little depth with the relative widths of the profile lands28, as compared with the spacing between the lands 28 and the side walls30 of adjacent profiles, being relatively narrow. At B-B in FIG. 1B, theprofiles have progressively deepened with the lands remaining the sameor substantially the same width while the spacing between the sidewallsof adjacent profiles has become narrower. At C-C of FIG. 1C, theprofiles 22 have reached the full depth of the profile to be formed onthe workpiece 'and this cross-sectional configuration of the fonningprofiles continues to the exit of the tool. The lands 28 are ofsubstantially the same width as at section AA. However, it is to benoted that the width of the profiles for a given radial distance fromthe centerline of the flex ring has increased to its maximum widththereby farther decreasing the spacing between the sidewalls 30 ofadjacent profiles for a given radius.

FIGS. 2 and 3 illustrate one type of apparatus with which the flex ringforming tool 20 of the present invention can be used to produceexternally profiled workpieces by material flow of displacement.

Two or more rolls 2 and 3 act on the circumference of the flex ring 20to deflect the ring inwardly to apply pressure to the workpiece W. Theserolls 2 and 3 are carried on slides 4 and 5 which are fed inwardly byany appropriate means as is well known in the art, such as feed screwsor hydraulic means if desired.

As shown in FIG. 2, the rolls 2 and 3 are mounted in bearings 6, 7, 8,and 9 which are carried in slides 4 and 5. The rolls 2 and 3 are free torotate in these bearings upon contact with the workpiece W.

The flex ring 20 is held against axial movement relative to rolls 2 and3 by a thrust member 10 acting through member 11 against the end 26 ofthe flex ring 20.

The member 10 acts against thrust bearing 12 and is rotatable in radialbearings 13 and 14.

The workpiece W is fed into and rotated by any suitable mechanism. Asshown in FIG. 2, this consists of a work driver 15 which forces theworkpiece W into the flex ring while simultaneously rotating theworkpiece. The rotation of the workpiece W causes the flex ring 20 torotate and the rotation of the flex ring 20 causes the freely mountedrolls 2 and 3 to also rotate.

If desired, it should be apparent that instead of rotating the workpiecepositively, one or both of the rolls 2 and 3 may be positively rotatedin which case, the rolls impart rotation to the flex ring 20 and theworkpiece W so as to obtain the desired deflection of the flex ring 20in the necessary localized circumferentially displaced areas.

It will be apparent that as the flex ring 20 rotates between the rolls 2and 3 adjacent areas of the outer circumference of the ring pass throughthe deflection area of the deflection rolls 2 and 3 and as these areaspass through the deflected zone pressure will be applied in limitedzones to the workpiece W causing the material to flow radially outwardto gradually conform the work to theinternal profile of the flex ring 20as shown in FIG. 1D.

The radial outward flow of the material of the workpiece W will occur inthe deflection zones and in these locations, the

workpiece will be flowed in a direction to conform to the profiles ofthe flex ring 20 and to be complemental to the flex ring 20. Flow willoccur only where pressure is applied; that is, in the deflection zone.

The pressure applied by the rolls 2 and 3 to the flex ring 20 aresufficient in magnitude to exceed the yield strength of the workpiecematerial in the localized deflection zones and in localized areas andthis causes a flow of plastic material which progresses in incrementalsteps both-circumferentially and axially as the workpiece is fed intothe flex ring 20. This flow continues until the final finished profileis produced on the workpiece as shown in FIG. 1D whereby the peripheralshape of the workpiece has changed from its originally circular profile32 to the complement of the flex ring profile having teeth T.

The incremental feeding is dependent upon the speed of rotation throughthe deflection zones and the amount of deflection of the flex ring 20.The application of force in localized deflection zones or areas of theflexring circumference together with the unique structure of the flexring forming tool avoids stressing of the entire cross section of theworkpiece thus allowing the workpiece material to flow radially outwardas the axial feed and the rotation progress. In addition to ensuring aprimarily radial configuration of the workpiece material, the uniqueconfiguration of the flex ring forming tool 20 of the present inventioninhibits any longitudinal flow of the material.

FIG. 3 shows the formation of a workpiece in apparatus such as disclosedin FIG. 2. In FIG. 3, the deflection of the flex ring 20 is shown ingreatly exaggerated form. It will be seen from this FIG. 3 that thematerial of the workpiece W is forced radially outward into the spacesof the portions of the flex ring 20 which are being forced inwardly bythe pressure exerted radially inward by the force of the rolls 2 and 3acting on the flex ring 20 in the localized pressure zones.

The accuracy of the flex ring 20 is directly reflected in the accuracyof the workpiece since the workpiece is the complement of the contour ofthe flex ring. Since no generating action is involved nor any conjugateaction between workpiece and tool, the workpiece obtained by the presentinvention is a true complement or negative of the flex ring.

Moreover, due to the fact that the dimension X, as shown in FIGS. 1Athrough 1D, is constant throughout the axial length of the flex ring,the outside diameter of the workpiece tooth is rigidly controlledthroughout the forming operation and no flaking or seaming will occur onthe tip of the tooth due to any undesirable outward material flow.

While the preferred form of the invention has been shown and described,it is to be understood that all suitable modifications and equivalentsmay be resorted to which fall within the scope of the invention.

What is claimed is:

l. A forming tool for forming a profile on a workpiece comprising: aflexible element having an opening therein adapted to receive aworkpiece to be fed axially relative to said opening, said opening beingperipherally defined by a plurality of inwardly projecting and generallyaxially extending forming profiles, said forming profiles having inner.terminal lands of substantially constant widths.

2. The forming tool of claim 1 wherein said forming profiles haveportions adapted to make initial contact with the workpiece and each ofsaid forming profiles have a minimum depth at said portions.

3. The forming tool of claim 1 wherein said forming profiles haveportions adapted to make initial contact with the workpiece and wherein,for a specified depth, said forming profiles have their minimum widthsnearest said portions.

4. The forming tool of claim 1 wherein the axially extending formingprofiles are substantially straight.

5. The forming tool of claim 1 wherein the axially extending formingprofiles are helical.

6. The forming tool of claim 1 wherein said forming profiles haveportions adapted to make initial contact with the workpiece, each ofsaid forming profiles having a minimum depth at said portions and saidforming profiles, for a specified depth, having their minimum widthsnearest said portions.

7. A forming tool for forming a complementary profile on a workpiececomprising: a flexible element having first and second end faces, saidelement having an opening therein extending between said end faces andadapted to receive a workpiece to be fed axially relative to saidopening, said opening being peripherally defined by a plurality ofcircumferentially spaced, and inwardly projecting forming profiles, saidforming profiles extending in a generally axial direction and havingleading end portions adjacent said first end face adapted to makeinitial contact with the workpiece, said forming profiles having innerterminal lands of substantially constant width, said forming profilesincreasing in depth from said leading end portions to maximum depthsintermediate said first and second end faces, and, for a given depth,said forming profiles increasing in width from said leading end portionsto maximum widths intermediate said first and second end faces.

* i I! I i

1. A forming tool for forming a profile on a workpiece comprising: aflexible element having an opening therein adapted to receive aworkpiece to be fed axially relative to said opening, said opening beingperipherally defined by a plurality of inwardly projecting and generallyaxially extending forming profiles, said forming profiles having innerterminal lands of substantially constant widths.
 2. The forming tool ofclaim 1 wherein said forming profiles have portions adapted to makeinitial contact with the workpiece and each of said forming profileshave a minimum depth at said portions.
 3. The forming tool of claim 1wherein said forming profiles have portions adapted to make initialcontact with the workpiece and wherein, for a specified depth, saidforming profiles have their minimum widths nearest said portions.
 4. Theforming tool of claim 1 wherein the axially extending forming profilesare substantially straight.
 5. The forming tool of claim 1 wherein theaxially extending forming profiles are helical.
 6. The forming tool ofclaim 1 wherein said forming profiles have portions adapted to makeinitial contact with the workpiece, each of said forming profiles havinga minimum depth at said portions and said forming profiles, for aspecified depth, having their minimum widths nearest said portions.
 7. Aforming tool for forming a complementary profile on a workpiececomprising: a flexible element having first and second end faces, saidelement having an opening therein extending between said end faces andadapted to receive a workpiece to be fed axially relative to saidopening, said opening being peripherally defined by a plurality ofcircumferentially spaced, and inwardly projecting forming profiles, saidforming profiles extending in a generally axial direction and havingleading end portions adjacent said first end face adapted to makeinitial contact with the workpiece, said forming profiles having innerterminal lands of substantially constant width, said forming profilesincreasing in depth from said leading end portions to maximum depthsintermediate said first and second end faces, and, for a given depth,said forming profiles increasing in width from said leading end portionsto maximum widths intermediate said first and second end faces.